DE 199 084 40 A1 discloses an electromagnetic hydraulic valve of a generic type that is configured as a 3/2 directional switching valve and generally comprises an electromagnet with an axially movable armature and a valve part with at least two valve seats and a closing ball that corresponds to at least one valve seat. The electromagnet is formed by a hollow cylindrical plastic coil spool with an electric plug contact, at least one coil winding received in the coil spool and a magnet housing surrounding the coil winding, the hollow cylinder of the plastic coil spool being configured at least partially as an armature space for the armature, which armature space is lined with a non-magnetic metal sleeve. The magnet housing of the electromagnet, in contrast, is configured as a cylinder tube sleeve whose one front end is angled into the interior of the sleeve to form a circular ring-shaped bottom and whose other front end comprises a plurality of turn-over tabs through which the magnet housing is connected to the plastic coil spool that can be inserted into the magnet housing. Further, a metal disk cast into the plastic coil spool and a pole core inserted into the hollow cylinder of the coil spool form an upper pole of the electromagnet, while its lower pole is formed by an extension of the valve part of the hydraulic valve, which extension can be inserted into the hollow cylinder of the coil spool and is conductively connected to the magnet housing through the bottom thereof. The valve part substantially comprises a hollow cylindrical valve housing that has a pressure delivery connection on one front end, as also a load connection and a tank connection that are made as radial holes in the cylinder jacket of the valve housing. Inside the hollow cylinder of the valve housing is arranged respectively between the pressure delivery connection and the load connection, and between the load connection and the tank connection, one of the valve seats of the valve part. Both valve seats are made as axial apertures in the bottoms of two cup-shaped deep-drawn parts that are fixed with their peripheral surfaces in the hollow cylinder of the valve housing and are connected to each other by a plastic sleeve. The loosely arranged closing ball of the valve part, that is operatively connected to the armature of the electromagnet through a tappet, is guided in this plastic sleeve. Through a compression spring arranged between the electromagnet and the pole core of the upper pole, the armature exerts, in a non-energized state of the electromagnet, a constant biasing force on the closing ball for closing the pressure delivery connection of the hydraulic valve. This hydraulic valve, thus configured as a magnetic pull valve, can be inserted with the valve part that comprises a plurality of outer sealing rings into a complementary valve reception. The hydraulic valve comprises a separate fixing flange which is arranged between the electromagnet and the valve part and through which the hydraulic valve can be screwed, pressure-medium tight, on the valve reception.
A drawback of this prior art electromagnetic hydraulic valve, however, is that it is composed of a relatively large number of separate parts some of which, for example the magnet housing and the valve seats, can certainly be made without chip removal. Other parts, however, like the valve housing of the valve part, as also the armature and the pole core of the upper pole of the electromagnet, have a relatively solid configuration and, due to their structural design, can only be fabricated by machining methods. However, due to the relatively long machine cycle times, the tools and equipment required and the material used, fabrication by machining methods causes considerable costs and, in the last analysis, has proved to be uneconomic. In addition, due to the large number of individual parts, the work and expense involved in the final assembly of the hydraulic valve are also increased so that, on the whole, the manufacturing costs of this prior art hydraulic valve can be expected to be disadvantageous.